1. Field of the Invention
The present invention generally relates to a top-change combination lock including a hasp movable between unlatched and latched positions relative to a latch and, more particularly, to enabling the opening combination of such lock to be changed only when the hasp is in the unlatched position.
2. Description of the Prior Art
Combination locks are conventionally employed on luggage cases, such as suitcases or attache cases, to hold the lid or cover locked closed until a set of combination dials are turned to a user-settable opening combination. Such locks conventionally include a hasp assembly mounted on the lid, and having a spring-biased hasp pivotable between unlatched and latched positions, as well as a lock assembly mounted on the main container of the case, and having a latch movable into and out of latching engagement with the hasp by a user-operated actuator button outwardly accessible to a user. The lock assembly includes a set of rotatable combination dials, each bearing numerical indicia and, when set to a predetermined opening combination, permit the button to be moved to a release or open position in which the latch is disengaged from the hasp, thereby releasing the hasp from its latched position and permitting the hasp to return under the restoring action of an internal hasp spring to its unlatched position. Such locks may be of the deadbolt type in which the latch does not move relative to the button but, instead, jointly moves with the button, or of the livebolt type in which the latch is movable relative to the button.
The opening combination is pre-set by the lock manufacturer, but the user has been given the option of changing the opening combination to any desired sequence of indicia, presumably to some easily remembered code. In one prior art approach, the lock assembly includes a control element which extends through a wall of the case and into the interior thereof. By manipulating the interior control element in this so-called "bottom-change" lock, the user can set the opening combination to any desired sequence by turning the combination dials.
Although generally satisfactory for its intended purpose, the bottom-change lock has not proven to be altogether satisfactory because of the expensive and time-consuming assembly procedure involved in mounting the lock assembly on the case. Also, it is awkward to change the lock combination from the interior of the case. In addition, it is unattractive to have control elements extending into the interior of the case.
In order to avoid such drawbacks, the prior art has also proposed so-called "top-change" locks wherein the user can set the code from outside the case. In one prior art approach, the actuator button itself is used as the control element to permit the opening combination to be changed. For this purpose, since the actuator button is typically moved in one axial direction away from the combination dials to disengage the latch from the hasp, now, for the purpose of changing the opening combination, the actuator button is moved in the opposite axial direction toward the combination dials. The dual uses of the actuator button, when pushed in opposite axial directions, makes for a very versatile lock whose opening combination is convenient to alter, and which is attractive in appearance.
However, drawbacks have arisen When the actuator button itself is used for changing the opening combination. One problem concerns itself with the non-return of the button. Thus, the actuator button is normally maintained in a central position under the influence of a return spring within the lock assembly. When the hasp is in the latched position, the central position of the button defines a closed or locked position. When the button is pushed to the left away from the combination dials to the aforementioned release position, the latch is moved to the left and the hasp is unlatched. When the actuator button is released by the user, the button returns to the central position under the influence of the return spring.
Now, if the opening combination is to be changed, the user pushes the button to the right toward the dials to a combination-changing position. In the case of a deadbolt lock, the latch is also moved jointly to the right. While holding the button in the combination-changing position, the dials are turned as desired to the new opening combination. Once the button is released from the combination-changing position, it is returned by the return spring to the central position.
The problem has arisen in the prior art that the actuator button, in some cases, does not readily return from the combination-changing position to the central position. Although the return spring is supposed to automatically return the button to the central position, this does not always occur. Sometimes, when the hasp is in the closed position, the latch, which is jointly moved to the right when the button is moved to the combination-changing position, jams up against the hasp due to mechanical interference therewith. The restoring force of the return spring is sometimes insufficient to overcome this mechanical interference, with the result that the button becomes "stuck" in the combination-changing position. This sticking problem is particularly aggravated when the hasp is not properly aligned with the corresponding hasp opening in the lock assembly, which situation often occurs due to poor assembly procedures, or when the hasp assembly is placed on a lid wall which is either not flush, or is in some way misaligned, with the adjacent case wall on which the lock assembly is mounted. The lid wall and/or the adjacent case wall may have a rounded curvature which further worsens hasp alignment. The button-sticking problem could perhaps be overcome by providing the return spring with a higher spring characteristic, but this would only increase the force necessary to push the actuator to the release position and, hence, this is an undesirable solution.
Thus, experience has shown that the actuator button could either be deliberately or inadvertently moved to the combination-changing position, and the user could be unaware that the actuator button did not automatically return to the central position, in which event, further turning of the dials, either deliberately or inadvertently, would change the opening combination, perhaps to a sequence which is unknown to the user. Should this series of events occur when the hasp is in the latched position, the case would be locked and could not be opened because the user would be unaware of the opening combination.
In an attempt to provide at least a limited measure of relief against such a chain of circumstances, one prior top-change lock approach utilizes a livebolt design so that the lock can be picked by gaining access to the latch and pushing the latch out of latching engagement with the hasp. In another livebolt design according to the prior art, the actuator button itself is locked in the combination-changing position, and the user is compelled to affirmatively push the button back to the central position--a situation which is not always practiced, easily forgotten and usually ignored, and generally so inconvenient a procedure that the user often is reluctant to change the opening combination.
In the prior art top-change combination locks of the deadbolt type, since the lock cannot be picked by sliding the latch out of latching engagement with the hasp, the art has proposed a discrete control actuator which is separate from the actuator button. Thus, in this deadbolt design which, of course, is a more secure lock because of the inability to pick a deadbolt lock, two actuators must be operated in a certain sequence to change the opening combination. Experience has shown that it is awkward and complicated to perform this combination-changing procedure, with the result that the typical user prefers to keep the original opening combination rather than go to the trouble of changing the opening combination.
In addition, broken fingernails are unhappy by-products of the latter-described lock. Also, the use of two actuators renders the lock unattractive in appearance and expensive in construction.